<template>
  <div class="detail-header">
    <router-link tag="div" to="/" class="header-absolute" v-show="showAbs">
      <div class="iconfont header-absolute-back">&#xe624;</div>
    </router-link>
    <div class="header-fixed" v-show="!showAbs" :style="opacityStyle">
      <router-link to="/">
        <div class="iconfont header-fixed-back">&#xe624;</div>
      </router-link>
      景点详情
    </div>
  </div>
</template>

<script>
export default {
  name: 'DetailHeader',
  data () {
    return {
      showAbs: true,
      opacityStyle: {
        opacity: 0
      }
    }
  },
  methods: {
    handleScroll () {
      // 获得滚动条位置
      let top = document.documentElement.scrollTop
      if (top > 45) {
        let opacity = top / 100
        opacity = opacity > 1 ? 1 : opacity
        this.opacityStyle = { opacity }
        this.showAbs = false
      } else {
        this.showAbs = true
      }
    }
  },
  activated () {
    window.addEventListener('scroll', this.handleScroll)
  },
  deactivated () {
    window.removeEventListener('scroll', this.handleScroll)
  }
}
</script>

<style lang="stylus" scoped>
  @import '~styles/variable.styl'
  .header-absolute
    position: absolute
    top: .2rem
    left: .2rem
    width: .72rem
    height: .72rem
    line-height: .72rem
    background: rgba(0, 0, 0, .8)
    border-radius: .36rem
    text-align: center
    .header-absolute-back
      color: #FFFFFF
      font-size: .36rem
  .header-fixed
    z-index: 90
    position: fixed
    top: 0
    left: 0
    right: 0
    height: $headerHeight
    line-height: $headerHeight
    text-align: center
    font-size: .32rem
    color: #FFFFFF
    background: $bgColor
    .header-fixed-back
      position: absolute
      top: 0
      left: 0
      width: .8rem
      font-size: .36rem
      font-weight: bold
      text-align: center
      color: #FFFFFF
</style>
